Publication

New ATLAS publication

Measurement of the tttt production cross section in pp collisions at sqrt(s)=13 TeV with the ATLAS detector” has been submitted to JHEP. Members of the IFAE-ATLAS team (Aurelio Juste, Nicola Orlando, and Anil Sonay) have played a leading role in this publication, from designing the analysis strategy to the final multivariate technique and statistical analysis employed.

This paper presents a measurement of the four-top-quark production cross section in final states with a single lepton or an opposite-sign lepton pair in association with multiple jets using the full Run 2 dataset collected with the ATLAS detector. With four top quarks produced per event, this is a very rare Standard Model process with a predicted cross section of only 12 fb, and thus is very sensitive to beyond-the-SM (BSM) contributions. A sophisticated event categorization and multivariate technique is used to discriminate signal from background events. The result of this analysis is combined with a previous measurement in multilepton final states. The combined cross section is measured to be a factor of two higher than the SM prediction, although compatible with it within 2.0 standard deviations. The corresponding observed (expected) signal significance is .7 (2.6) standard deviations over the background-only prediction.

The IFAE team is currently working on an improved analysis targeting BSM production of four-top-quark events. Stay tuned!

More information on the ATLAS Physics Briefing

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Latest Group News

New Member

New Member in the ATLAS group

November 23, 2021

Jack Harrison has just joined the ATLAS group as a PhD student with an INPhINIT Fellowship.

Instrumentation Milestone

HGTD project milestone achieved

October 6, 2021

Wafers with the ALTIROC2 chip were received this week. This is a major milestone for the HGTD project.R. Casanova played a leading role in the design of the digital part of the chip and its verification.

New Position

Martine Bosman elected as a Fellow of the European Academy of Sciences

October 6, 2021

Martine Bosman was recently elected as a Fellow of the European Academy of Sciences (EurASc). EurASc is a fully independent international association of distinguished scholars that aims to recognize and elect to its membership the best European scientists with a vision for Europe as a whole, transcending national borders, and with the aims of strengthening European science and scientific cooperation.